COMPARISON OF CD44 EXPRESSION IN EARLY COLORECTAL CARCINOMAS OF THE DE-NOVO AND EX ADENOMA TYPES

Small colorectal carcinomas without morphological evidence of origin f rom an adenoma have been called ''de novo'' carcinomas. As changes in the expression of the adhesion molecule CD44 and its variants have bee n described along the adenoma-carcinoma sequence in colorectal carcino ma, we compared patterns of CD44 expression in early de novo and ex-ad enoma colorectal carcinomas by staining specimens from a group of earl y (pT1) colorectal carcinomas by immunohistochemistry for CD44 (standa rd and variant forms v3, v5, v6, v7, v7/8, v10). We evaluated carcinom a, adenoma (exadenoma cases), transitional mucosal areas and apparentl y nonneoplastic mucosa peripheral to the lesions (when present). A mar ked increase was seen in numbers and intensity of standard and variant forms of CD44 in carcinomatous areas compared with nonneoplastic muco sa in both groups, with no significant difference between the groups. However, adenoma areas of the ex-adenoma cases and the transitional mu cosa of the de novo carcinomas had nearly identical staining patterns. Together with data from other molecular studies, this may be interpre ted as evidence for an adenoma-type precursor lesion in so-called de n ovo colorectal carcinomas.